In the case of guitars and similar stringed musical instruments it is well known to sometimes equip the instruments with tremolo devices operable by a player to periodically slightly vary the tension and/or length of the strings to cause the tones emitted by them to waver or fluctuate about the fundamental values selected by the stopping of the strings by the player's fingers.
By way of example, reference is made to U.S. Pat. No. 4,512,232 which shows a tremolo device. Typically in such devices the strings are anchored to a string anchor pivotal about a tremolo axis extending generally perpendicularly to the strings. The tension existing in the strings tends to rotate the string anchor in one direction about the tremolo axis, and one or more springs connected to the string anchor exert forces thereon tending to rotate it in the opposite direction about the tremolo axis in counteraction to the string tension. The springs and strings together bias the string anchor to a neutral position corresponding to the fundamental tuning of the strings. Attached to the string anchor is a tremolo arm engageable by the hand of a player and by means of which the player may rock the string anchor back and forth about the tremolo axis to create a tremolo effect wherein the tones produced by the strings are periodically varied slightly above and below the fundamental tuning.
The springs acting on the string anchor of a tremolo device are attached at their opposite ends to a spring anchor. It is known from U.S. Pat. No. 4,512,232, and from other prior tremolo devices, to make the spring anchor adjustable to allow the tension applied by the springs to the string anchor to be varied to suit the particular strings used with the stringed instrument. That is, different sets of strings may be used with the instrument and the total force applied by each set to the string anchor may vary from set to set. Therefore, if the spring anchor is properly set for one set of strings, at which setting the string anchor will be biased to a given neutral position about the tremolo axis at which the tremolo arm is at a desired disposition relative to the instrument top surface, the installation of another set of strings without changing the position of the spring anchor may cause the string anchor and the attached tremolo arm to depart from their desired neutral positions. This departure from the desired positions can be overcome by readjusting the position of the spring anchor to cause the tension imposed by the springs on the string anchor to better suit the forces imposed on the string anchor by the new set of strings.
Known mechanisms for adjusting the position of the spring anchor have, however, been difficult to operate and often require special tools and/or time consuming removal of cover plates or the like to gain axis to the mechanism.
The general object of the invention is therefore to provide an improved mechanism for setting and adjusting the counter-tension applied by springs to the string anchor of a tremolo device with such adjusting mechanism being simple to operate, using a commonly available tool and being capable of being adjusted without having to remove any cover plate or the like.
A further object of the invention is to provide a counter-tensioning mechanism of the aforegoing character which is relatively simple to manufacture, smoothly operating, and capable of being used with a wide variety of tremolo devices.
Other objects and advantages of the invention will be apparent from the following description of a preferred embodiment of the invention and from the appended claims taken in conjunction with the accompanying drawings.